Controlling vegetation



United States Patent Delaware No Drawing. Filed Oct. 8, 1956, Ser. No. 614,365

Claims. (Cl. 71-2-7) This invention relates to methods of destroying or controlling vegetation and to herbicidal compositions. More particularly it relates to methods of destroying or controlling vegetation which comprises applying thereto a vinyl ester of a phosphoroamidic acid.

General objects of the invention are to provide compositions which are toxic to living plants and to provide methods for their use. Another object is to destroy noxious vegetation either in the form of germinating seeds or by application of the toxicant to the foliage after emergence. Other and further objects will be apparent from the detailed description which follows.

The phytotoxic vinyl esters of phosphoroamidic acids comprise weed killers having both pro-emergence and post-emergence activity. Accordingly, by applying the toxicant to the plant is meant any means whereby the toxicant is brought into contact with living plants which latter include germinating seedlings, as for example by application to the ground before the plants emerge or by direct application to the foliage.

The active components of the new herbicidal compositions are characterized by the presence of at least one nitrogen atom attached directly to a phosphorus (V) acid ester in which the ester group is a vinyl or substituted vinyl radical. The chlorovinyl esters of tetraalkylor tetraalkenylphosphorodiamidic acids are preferred for reasons of economy, ease of preparation and outstanding activity. Vinyl phosphoroamidates may be prepared by condensing esters of phosphorus (III) amides with alpha halogenated aldehydes or ketones. It is now recognized that this reaction yields vinyl phosphates instead of the normal Michealis=Arbuzov reaction. However, this invention is not concerned with the method of synthesis and is not limited thereby.

Typical examples of herbicidally active esters comprise vinyl tetrapropylphosphorodiamidate,

2,2-dich1orovinyl tetrapropylphosphorodiamidate,

Z-chlorovinyl tetrapropylphosphorodiamidate,

2-bromovinyl tetraisopropylphosphorodiamidate,

2,2-dichlorol-trichloromethylvinyl tetrapropylphosphorodiamidate,

2,2-dichlorovinyl tetramethylphosphorodiamidate,

2,2-dibromovinyl tetraallylphosphorodiamidate,

2-chlorovinyl tetraethylphosphorodiamidate,

Z-chlorovinyl tetrabutylphosphorodiamidate,

2,2-dichlorovinyl tetraethylphosphorodiamidate,

l-dichlorofluoromethyl-2,2-difluoroviny1 tetrapropylphosphorodiamidate and 2,2-dichloro-l-pentylvinyl tetrapropylphosphorodiamidate.

The new toxicants may be applied conveniently in the form of a spray containing the active ingredient in a concentration within the range of 0.1% to 10% by weight. Thorough coverage of the foliage is desirable. Both grasses and broadleaved plants are effectively controlled. Weeds from the following plant families are controlled to varying degrees: Leguminoseae, Cucurbitaceae, Umbellifereae, Chenopodiaceae, Amaranthaceae, Convolvulaceae and Polygonaceae. For pre-emergence application amounts within the range of 10 to 60 pounds per acre are recommended.

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Most of the chlorovinyl tetraalkylphosphorodiamidates are insoluble in water but they are soluble in common organic solvents. They may be dispersed directly in water or dissolved first in an organic solvent and then dispersed. As dispersing and wetting agents there may be employed soft or hard sodium or potassium soaps, alkylated aromatic sodium sulfonates such as sodium dodecyl benzene sulfonate, or an amine salt or dodecyl benzene sulfonic acid, alkali metal salts of sulfated fatty alcohols, ethylene oxide condensation products of alkyl phenols or tall oil and other dispersing and wetting agents. The herbicides may be formulated and applied as dry compositions by mixing the toxicant with a finely divided solid carrier, as for example talc, clay, pyrophyllite, silica and fullers earth. Alternatively, the dry, solid, freeflowing mixture of the chlorovinyl phosphorodiamidate and solid carrier may be dispersed in water and applied as a spray.

The tables below illustrate characteristic herbicidal activity of typical chlorovinyl tetraalkylphosphorodiamidates. The toxicant was emulsified in water and the emulsion applied a spray. In the foliage tests the spray containing the concentration of the active ingredient shown in the table was applied to the foliage of grass Contact Preemergence No phytotoxiclty 0 0 Slight phytotoxiclty 1 1 Moderate phytotoxic 2 2 Severe phytotoxicity 3 3 Dead 4 Deioliation 6...... B

TABLE I Contact Phytotoxicity Rating 00110., Toxlcant Percent; Grass Bean Broadleaf 1 2,2-Dich1orovinyl tetraethyl- 0.5 3+ 3+ 4 phosphorodlamldate. 2 2,2-Dichlorovinyl tetrapro- 0.5 4 4 4 pylphosphorodiamidate. 3 2-Chlorovinyl tetraethyl- 0. 5 4 3+ 4 phosphorodiamldate. 4 2,2 Dlchloro 1 trichloro 0. 5 3+ 1+ 3+ methylvinyl tetrapropylphosphorodiamidate.

The plants employed in the pre-emergence tests are designated by letter in Table II. The plants corresponding to the letters are as follows:

F. Barnyard grass N. Annual morning glory G. Beet-sugar consisting of lower alkyl and allyl.

5. A method of destroying vegetation which comprises applying to the foliage thereof a phytotoxic concentration of 2-chlorovinyl tetraethylphosphorodiamidate.

6. A method of destroying vegetation which comprises TABLE II Pre-emergence" Phytotoxicity Rating CompoundNo. Lbs. per Acre A B O D E F G 11 3' K L M N It is intended to cover all changes and modifications applying to the foliage thereof a phytotoxic concentration of the examples of the invention herein chosen for purof 2,2-dichlorovinyl tetrapropylphosphorodiamidate. poses of disclosure which do not constitute departures 7. A method of destroying vegetation which comprises from the spirit and scope of the invention. applying to the foliage thereof a phytotoxic concentra- What is claimed is: tion of 2,2-dichlorovinyl tetraethylphosphorodiamidate.

1. A method of destroying vegetation which comprises 8. A method of destroying vegetation which comprises contacting the plant with a phytotoxic concentration of applying thereto a phytotoxic concentration of 2-chloro- 2,2-dichlonovinyl tetra (lower alkyl) phosphorodiamidate vinyl tetrapropyl phosphorodiamidate.- containing more. than one carbon atom in each 'alkyl 9. A method of destroying vegetation which comprises group. applying thereto a phytotoxic concentration of 2-bromo- 2; The method of claim 1 in which the toxicant is vinyl tetraalkyl phosphorodiamidate wherein the alkyl applied to the ground before the plants emerge. groups contain 3 carbon atoms.

3. A method of destroying vegetation which comprises 10. A method of destroying vegetation which comapplying to the foliage thereof a phytotoxic concentraprises applying thereto a phytotoxic concentration of 2,2- tion of Z-chlorovinyl tetra (lower alkyl) phosphorodidibrornovinyl tetraallyl phosphorodiamidate. V

amidate.

4. A method of destroying vegetation which comprises References cued the file Q thls Patem applying to the foliage thereof a phytotoxic concentra- UNITED STATES PATENTS tion of a halovinyl tetraalkylphosphorodiamidate con- 2,151,380 Flint et aL Mal. 21 1939 forming to the Struct 2,160,842 Dreyfus June 6, 1939 2,172,241 Dickey et a1 Sept. 5, 1939 2,502,966 Kosolapofi Apr. 4, 1950 R o 2,587,549 Trementazzi Feb. 26, 1952 I II/ R 2,623,611 Levine et al. 'De'c. 30, 1952 2,714,064 Morris et al. July 26, 1955 R 2,765,252 Pianka Oct. 2, 1956 2,814,636 Stahmann et a1. Nov. 26, 1957 R 1 40 2,848,492 Saul et a1. -Q. Aug. 19, 1958 where R and R are selected from'a group consisting of FOREIGN PATENTS halogen and hydrogen, R is selected from a group con- 505,253 Great B i i J l 20 194 sisting of hydrogen, lower alkyl and halogen substituted 591,353 Great B i i May 13 1953 methyl and R R R and R are selected from a group OTHER REFERENCES -Ramaswami et al.: Chemical Abstracts, vol. 46, col. l0244(e), 1952.

Capazzi: Chemical Abstracts, vol. 48, col. 2307(f), 1954, and corresponding Subject Index, page 1427. 

4. A METHOD OF DESTROYING VEGETATION WHICH COMPRISES APPLYING TO THE FOLIAGE THEREOF A PHYTOTOXIC CONCENTRATION OF A HALOVINYL TETRAALKYLPHOSPHORODIAMIDATE CONFORMING TO THE STRUCTURE 